ES2221506B1 - CD-AUDIO RECORDING PROCEDURE TO AVOID YOUR COPY. - Google Patents

Abstract

CD-Audio recording procedure to avoid copying. It includes the recording of consecutive tracks in which track 0 is an index that contains information on the position occupied by the rest of the tracks, in which the unit of recorded information is determined by a sector (1) after each one of which a symbol (2) composed of an array of eight PW channels containing information regarding the location of the sector (1) being reproduced is recorded; it is characterized in that the logical level of at least one bit of a group of bits of the P or Q channel is modified in at least one symbol of tracks 1-n, in which each group is constituted by sets of eight consecutive bits belonging to the same channel The modification provides the correct reading by an audio reader, but not by a CD-Rom reader or by an autonomous duplicator, avoiding the copy of the CD-Audio.

Description

Recording Procedure CD-Audio to avoid copying.

Object of the invention

The invention consists of a method for make the recording of a CD-Audio, which as it is expressed in the statement of this descriptive report, it has for object to avoid the subsequent copy of the CD-Audio.

The process of the invention is applicable to Any type of CD that includes audio. Therefore, the invention is applicable to CD-Audio as well as to those CDs in which audio tracks coexist with data tracks executable exclusively on a computer equipped with CD-Rom, as is the case with formats CD-Extra and CD-Mixed. Therefore, the invention is also applicable to the audio tracks that coexist with computer data, although not to the track or tracks of data included in the CD-Rom.

Background of the invention

In a CD-Audio the information is physically recorded in the form of pits that are incisions that determine differences in relief on the surface of the disk so that CD readers comprise a laser that is focused on the surface of the disk, which produces the laser reflection so that said radiation can be detected by a laser photodetector. So when the laser hits on a pit, there is no reflection on the photodetector, and of This mode can translate the disc information by the reader. The pits have eight different lengths, in order to build a complete code capable of representing the data at a resolution adequate.

From the logical point of view, the information is organized sequentially, so that the reading is done always from the beginning of the sequence to the end of it, and therefore there are no interruptions in reading.

In order to be able to access in a simple way to the data at an intermediate point, a plurality of consecutive tracks in which the zero track consists of an index (lead-in) containing position information that occupy the rest of the tracks, which are called the area of CD program and include data and / or audio. In addition, the unit of information recorded on each track is determined by a sector to continuation of each of which a symbol is recorded that is composed of a matrix of eight P-W channels that among other data it contains information regarding the location of the sector that is playing.

Each channel has a defined functionality such and as explained in the section of the embodiment preferred.

The set of the different symbols is called subcode.

This configuration facilitates the access to the pitas without the need to reproduce everything sequentially the volume of information from the beginning, and the players of audio generally allow direct access to the playback of the CD from a track, whose logical address. of beginning differs from the beginning of the disc.

\hbox{discográfica}

.On the other hand, the proliferation and reduction of the recorders, recording programs and recordable media has generalized the making of illegal copies among users, so that unauthorized copies are obtained by the owner of the contents of a CD, with the consequent damage economic that this represents for the author and the industry

 \ hbox {record} 

.

To make a copy, it is made generally by direct reading from the beginning until the end of all the sectors that make up the disk, and subsequently it is recorded exactly on a recordable disc.

In addition, it is increasingly common to compress digitally the sound contents of a CD and spread them on internet without authorization of the owner of said content, what which also implies significant damage to the industry and the Content owner.

The vast majority of copies of CD-Audio is done through computer equipment, so that the computer reader reads the information contained in each of the readers, later turning it over a recordable media and is the recording software used on responsible for automatically generating each of the symbols of subcode corresponding to each of the sectors of the disk final.

Another of the most used methods is that of autonomous duplicators. These types of devices consist of a reading unit and a CD recorder unit, so that the disk to be copied is inserted into the reading unit and it performs a dump on a virgin disc arranged in the recorder unit, of such that the replica is exact to the original.

Description of the invention

To solve the aforementioned problems, the invention has developed a new CD-Audio recording procedure to avoid its
copy.

It is experimentally demonstrated that if the subcode, and therefore the symbols that compose it from a CD-Audio, presents a very high proportion of errors High is impossible to play the disc in any reader. It can also be shown that if the same error affects a certain field of a symbol is repeated indefinitely in the successive symbols, the disk is equally illegible and by So much cannot be copied.

The behavior of audio readers (it means audio readers those who do not require a computer for operation as a sound player) is different than CD-Rom readers, in what referring to the response to subcode errors. By therefore, there is the circumstance that in certain combinations of errors present in the subcode, determine that the disk is illegible in many CD-Rom reading units, in so much that the same disc is perfectly reproducible in readers audio

This circumstance is of vital importance, since that the fact of being able to prevent the conventional reproduction of a CD-Audio disc in readers of CD-Rom, implies the impossibility of copying the disk or to compress the sound for broadcast on the internet, since reading, by computers, of the original disk is one of the most used methodologies for obtaining copies, as discussed in the previous section.

Likewise the mechanism incorporated in the readers of autonomous duplicators responds in the same way as CD-Rom readers face the mistakes of their code, so that copying of content is also prevented sounds through autonomous duplicators.

To achieve these objectives, the recording procedure of the invention is characterized in that the logical level of at least one bit of a group of bits of the P or Q channel is modified in at least one sub-code symbol of the program area (track 1- track n), in which each group consists of sets of eight consecutive bits belonging to it
channel.

In one embodiment of the invention only modify the logical level of a subcode group for each symbol of the P or Q channel, with the particularity that the modification performed is not done at the logical level of the same group corresponding to two consecutive symbols.

In an embodiment of the invention the modification of the at least bit of a group of the P channel consists of change a "0" to a "1" in the case of protection of a sound section, and a "1" for a "0" in the case of pause protection.

In addition, in the case of protection from a pause, no two consecutive "0" can be placed within a group; and in the case of sound protection should not be placed within a group two "1" in a row, since the presence of "1" consecutive on the P channel could determine that many readers of CD-Audio interpret the beginning of a pause in the protected point.

In the P channel, more than one bit can be changed as long as it does not affect two consecutive bits.

Regarding the Q channel, it should be noted previously, that this includes a control group formed by a CONTROL field and by another field conventionally known as ADR Thus, in the case where they have not been introduced modifications to the P channel, then they can be introduced in the Q channel, which according to an embodiment of the invention consists in that, in said control group of the Q channel, different values are set in successive symbols.

In another embodiment of the invention, in the group control of the Q channel the same values are set in successive Symbols

In either case of the modification performed on the Q channel, that is to say that in the control group set different values in successive symbols or set the same values in successive symbols, another group of this same is modified channel in the same symbol in combination with any of these two modifications.

In a preferred embodiment of the invention in the ADR field is modified according to the value "0001" since this combination indicates that the data included in the Q channel represents exact playback point information and track number reproduced, so that putting this value in the ADR field and by modifying the data of the Q channel, a modification of the data referring to the playing time.

In an embodiment of the invention the field of CONTROL is modified according to the value "X0XX", where X "0" or "1" to represent audio information, since whenever the second bit of the CONTROL field is a "0" indicates that the information is audio and therefore this modification does not affect Audio playback

In a preferred embodiment of the invention at perform the modification of a group of the Q channel are not modified the groups corresponding to the CRC (Cyclic Redundancy Code) of that channel.

In combination with the modification of the P channel or of the Q channel of all the described embodiments, can be modify the data of the R-W channels in one or Various symbols

These R-W channels are made the same modifications in two consecutive symbols or make different modifications in two symbols consecutive.

In this way, with the modifications made, the recorded CD-Audio is achieved can be read by an audio reader, and instead cannot be read by a CD-Rom reader or a duplicator autonomous, avoiding its copy.

Next to facilitate a better understanding of this descriptive report and being an integral part of the same, they accompany a series of figures in which with illustrative and non-limiting nature the object has been represented of the invention.

Brief statement of the figures

Figure 1.- Shows a schematic representation of the position that the symbols occupy with respect to the sectors that They precede them.

Figure 2.- Shows a schematic representation of the matrix that constitutes each of the symbols in which the columns constitute the P-W channels and rows the different bytes that constitute it.

Figure 3.- Shows a schematic representation of the structure of the Q channel.

Figure 4.- Shows a schematic view of the structure of the data field included in the Q channel.

Description of the preferred embodiment

Below is a description of the invention based on the figures discussed above.

As already described in the section on background of the invention sector 1 of a CD-Audio, constitutes the minimum unit of access information that is 2352 bytes in size that It is equivalent to 1/75 seconds of sound information.

Apart from the sound information, the sector comprises a compressed copy of said sound information for allow recovery in case the information part sound is illegible or will not match the summary information, in such a way that the missing data or errors of the sound information, without the CD user perceiving any error at the audition

Following each sector, a symbol 2 (figure 1), so that the set of all Symbols constitutes a subcode.

The size of each symbol is 96 bytes per sector, and are arranged as eight channels of information they receive the name P-W.

Figure 2 shows the assignment mode of each channel within a subcode symbol. In this figure you Note that for each byte of information, each channel will a bit corresponds, so that each symbol is constituted by a matrix of 96 x 8 bits.

Therefore, the subcode will consist of the information contained in each of the matrices of the Symbols

The following describes generically the meaning that conventionally have the channels that they constitute the columns of the symbol, in order to facilitate a better understanding of the process of the invention.

The P channel contains information regarding the track changes location (the track concept was explained in the background section of the invention) provided by the index located at the beginning of a CD (track 0). When a track ends the P channel sets its value with bits equal to "1" for at least two seconds, so that the bits of all symbols during that period of time have their P channel set to "one". This means that during the rest of the time in which do not expect a change of track the information of the P channel will be equal to "0".

The structure of the Q channel is represented in the Figure 3, and this comprises four different fields:

1) A CONTROL 3 field that is composed of four bits located at the beginning of the subchannel that provide information on the nature of the information contained in the sector 1. For CD-Audio the most used modes of This field are as follows:

- 0000 to indicate audio on two channels without pre-emphasis and that copying is prohibited.

- 0010 to indicate audio on two channels without Pre-emphasis and copying is allowed.

2) A second ADR 4 field that has three possible values, representing each of these values the nature of the information contained in the channel data, which corresponds to the next field as it will be described.

- ADR = 0001, represents mode 1 and indicates that the data in the following field represent point information Exact playback and the number of tracks played.

- ADR = 0010, represents mode 2 indicating that the Q data represents information related to the code UPC-EAN, which is a code that is sometimes used in  CD-Audio to identify the volume and assign it to a reference. This number is widely used by the industry record to identify the record house, year of publication, etc.

- ADR = 0011 represents mode 3, which indicates that the Q data represents information related to the ISRC code (International Standard Recording Code), which is a code that in Sometimes it is used on CD-Audio to identify each One of the clues and assign them to a reference. These numbers are widely used by the record industry to identify each topic musical, record house, year of publication, etc.

3) The following field refers to the data of Q and occupy 9 bytes in which one type or another of information, depending on what is expressed by the ADR field, as and As previously commented. For the invention only It is necessary to describe when ADR equals 0001, that is when refers to mode 1, in which case the structure of the data field Q It is represented in Figure 4 and contains the following bytes:

The reference number 7 indicates the TNO value that Define the track number. Its value is 00 for the index (track 0 where the track index is recorded) and AA for the index of output or band located after the last track (track n) that indicates the end of the disc

The reference number 8 indicates the second byte which is called X and refers to the track subscript. When a track has no subscripts, ie separations of a track that allow you to locate a specific part of a song within a clue, the value of TNO is 01. For pauses this value is 00.

The numerical reference 9 is composed of bytes 3, 4 and 5 and indicates the position within the program area measured in units of playing time corresponding to sector attached to this symbol, expressed in minutes, seconds and sectors.

The reference number 10 indicates the sixth byte and this must always be set to 0 by definition.

The numerical reference 11 refers to the bytes 7, 8 and 9 indicating the position within the disk measured in playback time units corresponding to the attached sector to this symbol, expressed in minutes, seconds and sectors. There is usually a difference between the time represented by reference 9 and this one of two minutes.

4) The last field has been referenced with 6 and it is the CRC (Cyclic Redundancy Code) of Q and is composed of two bytes in which the information is stored summary that allows you to recover data from the Q channel when they exist differences between what is expressed by data field 5 and the field CRC 6.

If fields 5 and 6 are damaged at the same time, the Subchannel information would be unrecoverable, since no There would be a possibility to find a way to replace the data. By both in no case can the data of the field 5 and 6, since in this case you could not recover the information.

Regarding R-W channels it fits point out that these are the ones used to transport, generally, text information relative to the hint in reproduction, subject title, etc., this information is represented in some audio readers, such as in CD formats known as CD-TEXT.

The ninety-six sets of six bits represented in each symbol by these R-W channels they are divided into groups of twenty-four in which represents text information and parity A and B. In the block of parity A represents the summary information that allows the data recovery from the position of every three. In the block of parity B represents the summary information that allows retrieve data from zero position to twenty three. The data recovery by parity indicates that if the number of about logical is even the parity information will be presented as a "0", while if it is odd, it is a "1".

Up to this point the concepts have been explained basic ones that are conventionally used in CD-Audio, and then proceed to perform the description of the process of the invention.

As noted above, if introduce certain errors in a CD-Audio, there may be the fact that it is readable by a reader of audio and not by a CD-Rom reader or a duplicator autonomous, achieving the desired effect so as to prevent the CD-Rom copy, as already commented in advance

For this, the method of the invention comprises modifying the logical level of at least one bit of a group of bits of the P or Q channel in at least one subcode symbol of the program area (track
1-track n) in which each group consists of sets of eight consecutive bits belonging to the same channel. Thus each channel comprises twelve groups.

Thus, the first eight bits of the P channel are denominate group 1, and successively until 12, so that the first eight bits of the Q channel belong to group 13 and the last eight bits of the W channel correspond to group 96.

The process of the invention provides that modifications that constitute errors can be made in all the bits of a group, except in the restrictions that later They will be described.

The process of the invention provides that Only modifications should only be made on the tracks 1 to n, and never on track 0, that is, it should not modify the index of tracks, nor should the data sectors

In the case where the modification is made the following rules must be followed on the P channel:

- Only the logical level of a group will be modified For each symbol. In other words, a symbol should not have two groups with modified levels, since if this were done the percentage of errors would detect an end of track where not really there is, so there could be problems to make your reading Through an audio reader.

- The same modification must not be made in the logical level of the same group number in two symbols consecutive, since the repetition in two consecutive symbols could mean a non-existent end of track for readers of audio, which means that if a given symbol was modified group 2 by including the value 00100010, the next symbol group may not undergo the same modification so that it can be read by an audio reader.

- In each modified group, a minimum of one bit, going from "0" to "1" in the case of the protection of a stretch of sound and "1" to "0" for the Case of protecting a pause.

- In the case of protection from a pause, no they will place, within a group, two consecutive "0", and in the Sound protection case will not be placed, within a group two "1" in a row.

For example, they will be valid, therefore, for Sound protection combinations:

"10100001" or "10001001" or "10000001"

For the protection of a pause they will be valid the combinations:

"01110111" or "11101101" or "01111110".

The presence of consecutive "1" values in the P channel could make many audio readers interpret the beginning of a pause at the protected point.

- As stated previously, it is not they will modify groups of P and Q simultaneously, since the Accumulation of errors in these channels generates in many readers Audio loss of control over playback.

If errors or modifications are introduced in The Q channel must meet the following conditions:

- Only the logical level of a group is modified for each symbol, that is, a symbol should not have two groups with modified levels, since if this circumstance occurs It would detect a track end where it really doesn't exist. This rule has an exception in group 13, corresponding to the fields of CONTROL and ADR 4 which may be set at certain values other than the original in successive symbols and in combination with other modifications of the Q channel.

Preferably the ADR field 4 will present the 0001 value, which, in combination with other modifications of the Q channel will offer an alteration of the time data of reproduction (minutes, seconds, sectors) referenced with 9 and 11 which will cause many CD-Rom readers to lose the Playback control In addition the control field 3 will present the X0XX values, where X can be "0" or "1", so that the information will be represented as audio.

- The same modification will not be made in the logical level of the same group number in two symbols consecutive, since the repetition of the same error in two symbols consecutive could mean a non-existent end of track for audio readers Obviously there is also an exception to this rule as stated above, which affects the fields 3 and 4.

- In each modified group, one will be modified minimum of one bit.

In a preferred embodiment they are not modified Groups 23 and 24 corresponding to CRC 6 of channel Q, set that the modification of these groups prevents when the Q channel it presents errors outside this system, for example defects that affect the bits of Q data or optical problems of reading, reconstruction of the Q channel is impossible, so that the Disk is illegible for all types of readers.

Regarding the R to W channels, it should be noted that these may be modified, within the same symbol, in several groups at the same time, in combination with the modification made in the P or Q channels described above.

In addition, these channels may repeat the same modifications in two consecutive symbols.

Claims (15)

1. CD-Audio recording procedure to prevent copying, which includes the recording of a plurality of consecutive tracks in which track 0 consists of an index (Lead-In) containing information on the position occupied by the rest of the the tracks that are called the Program Area of the CD (Data and / or Audio); and in which the unit of recorded information is determined by a sector (1) following each of which a symbol (2) is recorded that are composed of an array of eight PW channels that among other data contains information regarding the location of the sector that is being reproduced; each channel determining a column of the matrix and determining the information contained in the set of the different matrices a subcode; it is characterized in that the logical level of at least one bit of a group of bits of the P or Q channel is modified in at least one symbol of the subcode of the program area (track 1-track n, in which each group is constituted by sets eight consecutive bits belonging to the same channel. 2. CD-Audio recording procedure to avoid copying, according to claim 1, characterized in that only the logical level of a subcode group is modified for each symbol (2). 3. CD-Audio recording procedure to avoid copying, according to claim 2, characterized in that the modification made is not made at the logical level of the same group corresponding to two consecutive symbols. 4. CD-Audio recording procedure to avoid copying, according to claim 3, characterized in that the modification of at least one bit of a group of the P channel consists in changing a "0" to a "1" in the case of protection of a stretch of sound and a "1" for a "0" in the case of protection from a pause. 5. CD-Audio recording procedure to avoid copying, according to claim 4, characterized in that in the case of protection from a pause, two consecutive "0" cannot be placed within a group and in the case of sound protection not two consecutive "1" must be placed within a group. 6. CD-Audio recording procedure to avoid copying, according to claim 4, characterized in that more than one bit is changed as long as it does not affect two consecutive bits. 7. CD-Audio recording procedure to prevent copying, according to claim 3, wherein the Q channel includes a control group consisting of a CONTROL field (3) and another field conventionally known as ADR (4), characterized in that in said control group of the Q channel different values are set in successive symbols. 8. CD-Audio recording procedure to avoid copying, according to claim 3, characterized in that the same values are set in successive symbols in the Q-group CONTROL group. 9. CD-Audio recording procedure to avoid copying, according to claims 7 or 8, characterized in that in combination with the modification of the control group of the Q channel another group of this same channel is modified in the same symbol. 10. CD-Audio recording procedure to avoid copying, according to claim 9, characterized in that the ADR field (4) is modified according to the value "0001" so that in combination with other modifications of the Q channel the time data is modified Of reproduction. 11. CD-Audio recording procedure to avoid copying, according to claim 7, characterized in that the CONTROL field (3) is modified according to the value "X0XX", where X is "0" or "1" to represent the information of Audio. 12. CD-Audio recording procedure to avoid copying, according to claim 1, characterized in that when modifying a group of the Q channel, the groups corresponding to the CRC (6 Cyclic Redundancy Code) of said channel are not modified. 13. CD-Audio recording procedure to avoid copying, according to any one of the preceding claims, characterized in that the data of the RW channels is modified in one or more symbols. 14. CD-Audio recording procedure to avoid copying, according to claim 13, characterized in that the same modifications are made in two consecutive symbols in the data of the RW channels. 15. CD-Audio recording procedure to avoid copying, according to claim 13, characterized in that in the data of the RW channels different modifications are made in two consecutive symbols.